The actual BluRay weighs in at 43+GB and they used the space to give the movie a very high bitrate. The 10GB version will suck. There is a far better 17-18GB version out there in full 1080P with DTS core audio (The lossless DTS-HD being overkill for some and not compatible with some hardware players like the WDTV).
I will not buy a non-3D version anyhow. I plan on getting myself a relatively cheap 3D setup using a 24" 3D capable monitor and Nvidia shutter glasses costing around Â£400-Â£500. By sitting close to the screen anyhow I don't really need a 50" 3D HDTV that costs over Â£2000
What will be interesting is when we see 3D rips turning up in MKV containers or variants thereof. From what I can tell someone needs to tweak the encoder and container to allow an MVC type system as employed on BluRay (MVC does not require two video streams and thus does not take up twice the space needed). If you rip a 3D title to hard disk right now you will get a file twice the size of the BluRay. Unless you keep it as an ISO that is.